During the course of a day, an average person takes in approximately 500 milliliters of air per breath. For each breath taken, a person can inhale numerous types of airborne particles, including dust, pollen, mold spores, bacteria, etc. These particles consist of particulate matter in the form of microscopic solids and liquid droplets. This matter can potentially carry harmful diseases, causing irritation, allergic reactions, and disease. Types of diseases which are carried by airborne particles include tuberculosis, chickenpox, measles, and influenza.
The size of airborne particles is related to their potential harm. Smaller particles, for example, those less than 10 micrometers in diameter, are known to cause the greatest harm. These particles can migrate into a person's lungs and bloodstream, potentially affecting vital organs.
Conventional methods of preventing the inhalation of airborne particles are often limited by particle size. Mesh filters worn over a person's mouth, for example, prevent inhalation of large airborne particles. These larger particles, however, are merely irritants and generally will not have a long-term impact on health. While conventional filters can function well for their intended purpose, they generally are not effective in preventing the inhalation of smaller airborne particles. The inhalation of smaller airborne particles, particularly those that are less than 10 microns is, therefore, still a concern.